title: A 31P-NMR study of mono- and dimagnesium complexes of adenosine 5'-triphosphate and model systems.
abstract: 31P-NMR chemical shifts and spin-lattice relaxation times of ATP (adenosine 5'-triphosphate), ribose 5'-triphosphate and tripolyphosphate show closely similar behaviour in aqueous solution at pH 7.5 on titration with Mg2+. The results are interpreted in terms of formation of 1 : 1 and 2 : 1 (dimagnesium) complexes with Mg2+ bound exclusively to the triphosphate chain. Stability constants for these complexes are reported. It is suggested that the predominant form of the 1 : 1 complexes has Mg2+ bound in tridentate manner (via non-bridging oxygen) to the alpha, beta and gamma phosphorus atoms; whilst that of the 2 : 1 complexes has each Mg2+ bound in bidentate manner, one to the alpha and beta, and the other to the beta and gamma, phosphorus positions.
mesh_terms: D000255:Adenosine Triphosphate; D008274:Magnesium; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D008958:Models, Molecular; D010428:Pentosephosphates; D011122:Polyphosphates; D012266:Ribose / Q000031:analogs & derivatives
chemical_list: D010428:Pentosephosphates; D011122:Polyphosphates; C025202:ribose-5-triphosphate; D012266:Ribose; D000255:Adenosine Triphosphate; D008274:Magnesium; C005692:triphosphoric acid